Adds the command to the interop test runner to run the jwt ruby auth test cmd

tools/gce_setup/grpc_docker.sh

@@ -1150,6 +1150,23 @@ grpc_cloud_prod_auth_compute_engine_creds_gen_ruby_cmd() {
   echo $the_cmd
 }
 
+# constructs the full dockerized ruby jwt_tokens auth interop test cmd.
+#
+# call-seq:
+#   flags= .... # generic flags to include the command
+#   cmd=$($grpc_gen_test_cmd $flags)
+grpc_cloud_prod_auth_jwt_token_creds_gen_ruby_cmd() {
+  local cmd_prefix="sudo docker run grpc/ruby bin/bash -l -c";
+  local test_script="/var/local/git/grpc/src/ruby/bin/interop/interop_client.rb"
+  local test_script+=" --use_tls"
+  local gfe_flags=$(_grpc_prod_gfe_flags)
+  local added_gfe_flags=$(_grpc_jwt_token_test_flags)
+  local env_prefix="SSL_CERT_FILE=/cacerts/roots.pem"
+  env_prefix+=" GOOGLE_APPLICATION_CREDENTIALS=/service_account/stubbyCloudTestingTest-7dd63462c60c.json"
+  local the_cmd="$cmd_prefix '$env_prefix ruby $test_script $gfe_flags $added_gfe_flags $@'"
+  echo $the_cmd
+}
+
 # constructs the full dockerized Go interop test cmd.
 #
 # call-seq: